Wind power is increasingly popular due to its clean and environmentally friendly production of energy. The rotor blades of modern wind turbines capture kinetic wind energy by using sophisticated blade design created to maximise efficiency. However, complaints have arisen about the creation of noise associated with the operation of wind power plants. Hence, noise reducing devices and associated blade designs are increasingly desired.
One of the continued considerations for wind turbine blade design is the operational noise produced when such blades rotate, in particular for on-shore wind turbine installations. A portion of such noise is generated from airflow leaving the profile of a wind turbine blade at the blade trailing edge, and is often referred to as trailing edge noise.
As modern wind turbine blades are manufactured at increasingly longer blade lengths, the longer span of the blades results in higher relative wind speeds experienced by the blades. Accordingly, this can lead to relatively large levels of trailing edge noise.
To this end, modern wind turbine blades are sometimes provided with serrations along the blade trailing edges, in an effort to reduce blade trailing edge noise and/or to improve wind turbine blade efficiency, as can be seen in EP1314885. The serration are typically provided by attaching a serrated panel at the trailing edge of the wind turbine blade. While the noise mitigating properties of such serrations are advantageous, several drawbacks remain. Often, finding the right serration geometry is a trade-off between noise mitigation performance and structural requirements. This may lead to the need for thick trailing edge regions, especially near the serration base. This increased thickness has been found by the present inventions to become a potential source of additional noise.
Further, the panels may be rather stiff, which may lead to increased peeling forces and stress concentrations going into the laminate structure of the blade, in particular at the longitudinal ends of the panel.
There are several ways of attaching a panel to the trailing edge of the blade. US 2011/0142635 A1 describes a blade extension panel provided with a cutaway mounting portion for mounting the extension panel to the blade such that the blade extension is substantially flush with a surface of the blade. The cutaway portion defines a notch configured to locate the blade extension relative to the rotor blade. However, such an embodiment entails that the cutaway portion must be specifically designed for a specific portion of a wind turbine blade.
Accordingly, there is still a need to optimise the design of such serrations or trailing edge serration panels in order to maximise noise mitigation.
It is therefore an object of the invention to provide a wind turbine blade having an improved trailing edge configuration as well as a trailing edge serration panel for arrangement at the trailing edge of a wind turbine blade.
It is another object of the invention to provide a wind turbine blade design having serrations as well as a trailing edge serration panel, which design provide improved noise reduction during operation.